2. analog
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Help with my analog rig.

Recently, being bit with analogitis, I purchased the best sounding analog I ever had the pleasure of owning; VPI Classic 3, Lyra Kleos cartridge, and a Fosgate phono preamp. Everything sounds wonderful, EXCEPT....a constant low level hum (that increases with volume), and a problem with RF that seems to come and go.
Everything is plugged into a Running Springs Audio power conditioner. I've tried everything. This thing is haunting me. All of my cables are dressed and spaced apart properly.
I've been checking posts about analog noise, and there seems to be a lot of people experiencing the same problem as I am. Especially, if they are
using a tube phono preamp. The only thing I can think of is trying a Grant
Audio Ground Zero. According to what I have read, it will address the
hum problem, but I still may be left with the RF problem.
I absolutely love the sonic quality of the Fosgate, but if this tube preamp is the source of my noise problems, perhaps I should think about solid state. However, I love what these tubes are doing in my system!
Sorry if I keep rambling. Anyone out there have any suggestions or recommendations about what I can do?
In advance, thanks.
louisl
audioquest4life
773 posts
 
Are your IC's close to any power cables, especially the phono amps power supply? I had a similar issue a few weeks ago. I used grey pipe insulation that you can find at any hardware store as an experiment, and wrapped the phono IC's, and it worked to eliminate the hum. I would look at wrapping anything that crosses the path of the tube phono amp's cables. You will need to experiement. Last, make sure your are using the ground wire correctly from the tonearm cable. It should be grounded to the phono amp chasis.

Ciao,
Audioquest4life
manitunc
795 posts
 
I assume your toneam is grounded to the preamp and you have tried it without it being grounded to see if there is a change. Do you have the ability to plug your preamp into a different outlet from the tonearm or amp? One that is on a different circuit in your house? As for RF, is your tonearm cable shielded? What about your other ICs. I have only run into that problem with unshielded cables.
good luck. let us know.
snackeyp's avatar
snackeyp
455 posts
 
If I'm not mistaken low level hum is usually a ground issue. Is your abode a modern one or do you live in an old building? I know many old buildings do not have grounded electrical, so you need to find a true ground to tap into to overcome it. Also, all tube make noise, but this is usually not very noticeable unless the volume is up pretty high (on my Cary SLI-80 that is). Sometimes you will get a very noisy tube, however, so you might look into that. I almost bought a the Fosgate that you have until my local dealer told me that they are rather tricky to match the tubes to the desired sound. He did not mention hum or tube noise, only that this amp is pretty finicky and that tube rolling is part of owning one. I'm not sure what to tell you about RF. I get it as well but only through my phono section so I think it is the cartridge that picks it up, and it is not audible when playing music.
cmalak
681 posts
 
I would have your local dealer try to help you isolate the source of the hum. One usual suspect is the cabling. Are your ICs shielded? If you have no luck with your dealer, then definitely follow up with VPI and Fosgate customer service to see if they can help you pinpoint the source of the humm. My guess is they go through this a lot and are pretty good at diagnosing the source. Good luck.
xxqq250
43 posts
 
You have probably though of this already but you may have a gain mismatch between you cart and you phonopre. If you have other tubes, I would try them to rule out that yours may be bad. Also, I doubt this is your problem, but I had some noise issues and was able to take care of it with cables. When I used a very well shielded cable like Audioquest, it took care of the noise. Please understand, I hate recommending cables and urge you to try cables first and not buy them unless you are sure they fix the problem.
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